Trying to put a magpul asap on a 6 month old bushmaster M4gery. I can't get the nut lose. The castle nut does not appear to be staked, but I broke a castle nut wrench trying to get it lose. Is Bushmaster locktiteing the threads? I heated it up with a heat gun and put a lot of torque on the nut with no luck.

How much torque can I put on the lower in a magwell vice adapter without damaging the lower.

i had the same problem with mine a while back, its not locktited or stack, it was such a battle to get off. i mangled the nut but finally got it off with a 14" pipe wrench after trying with a stock wrench and heat with no luck. once i broke it free it didnt tread off easy the castle nut trashed the tube treads too, almost like it was cross treaded. never could figure out what the problem was

Thanks for the continued input. Wife fell off ladder, project delayed. I did order a better wrench. I will order a tube and nut and put some leverage on the casle nut wrench. If that does not work, the pipe wrench will come out of the tool box.

This must be the bad threading some spoke of.

How much force can I use with the lower in a vice using the block in the mag well device without breaking the lower?